1. Field of the Invention
The present invention relates to an apparatus and a method for drying washed objects, and more specifically, to an apparatus and a method for drying washed objects being suitable for washing, rinsing, and drying substrates of semiconductor wafers.
2. Description of the Related Art
Heretofore, removal of moisture entered in trenches is an important factor in drying of miniaturized washed objects such as wafers after washing of precision substrates, and thus a drying apparatus using organic solvent vapor is employed. An apparatus shown in FIG. 1 is known as a drying apparatus using organic solvent vapor.
The drying apparatus 1 includes, as shown in FIG. 1, a drying tank 2 being box-shape having an opening on top thereof in cross section, a heating device (heater) 3 mounted on the bottom surface 2a of the drying tank 2, a cooling coil 4 provided on the upper part of the drying tank 2, a solvent trap 5 provided downwardly of the cooling coil 4, a wafer placing table 7 disposed in the drying tank 2 for placing a wafer 6 as a washed object thereon, and a solvent pooling section 8 disposed downwardly of the wafer placing table 7.
The drying apparatus 1 heats organic solvent 9 charged into the drying tank 2 to a boiling point by the heater 3 and generates organic solvent vapor in the upper portion thereof. A wafer 6 already washed and rinsed with water is then inserted and arranged in the vapor in the drying tank 2. Condensation of organic solvent occurs on the surface of the wafer 6 that is inserted and arranged in the drying tank 2, and then moisture attached on the surface of the wafer 6 is replaced by organic solvent which is more likely to evaporate, whereby the wafer 6 is progressively dried. The wafer 6 in the organic solvent vapor is gradually increased in temperature to an evaporating point (boiling point), and then is taken out of the mist atmosphere, where attached solvent component rapidly evaporates due to its low latent heat, to be completely dried.
The organic solvent heated and vaporized by the cooling coil 4 disposed on the upper part of the drying tank 2 is condensed and dropped in the solvent trap 5 for recovery and reusing. Likewise, solvent including moisture dropped from the wafer 6 is also recovered in the solvent pooling section 8.
The drying apparatus 1 in the related art demands attention to flames since organic solvent is heated by the heater 3, and consumes a lot of energy because it carries out heating and cooling. In addition, it requires a significant period of time until a vapor layer is formed by being heated by the heater 3, and consumes a large quantity of organic solvent due to evaporation. Further, when the washed objects come in contact with the mist layer, heat of vapor (gas phase) is absorbed by the washed object, thereby causing abrupt change in phase (gas phase to liquid phase) and reducing the vapor layer. Consequently, the washed object is exposed to the atmosphere, which may easily results in contamination, insufficient drying, and so on.
Accordingly, it is an object of the present invention to provide an apparatus and a method for drying washed objects being capable of drying the washed objects in a reduced period of time, effectively preventing contamination of the objects, and preventing energy loss.
The apparatus for drying washed objects according to the invention includes a drying tank in which organic solvent mist is generated and supplied to washed objects therein, wherein the drying tank includes a mist-straightening vane for supplying organic solvent mist to the washed objects.
The mist-straightening vane of the apparatus for drying washed objects according to the invention is provided on the side wall of the drying tank, and is provided with a plurality of fine openings on the surface for emitting organic solvent mist at the position upwardly of a fluid spray nozzle away from a prescribed distance S, so that a portion of organic solvent mist that passed through the opening out of the whole part of organic solvent mist emitted from the fluid spray nozzle is indirectly emitted.
The fluid spray nozzle of the apparatus for drying washed objects according to the present invention can emit two or more different types of fluid simultaneously.
Fluid emitted from the fluid spray nozzle of the apparatus for drying washed objects according to the invention includes organic solvent mist and inert gas.
The configuration of the opening of the apparatus for drying washed objects according to the invention is chamfered configuration.
The apparatus for drying washed objects according to the invention includes a drying tank having an opening on top thereof so that the washed objects can be placed or taken out from above and a rinsing tank formed integrally with the drying tank, and is capable of being sealed hermetically by closing the openable and closable lid, and the drying tank includes a mist-straightening vane for supplying organic solvent mist to the washed objects.
The drying tank of the apparatus for drying washed objects according to the invention includes an overflow tank formed on top of the rinsing tank integrally for overflowing deionized water to be supplied into the rinsing tank, and a channel for drainage from the overflowing tank is grounded.
The apparatus for drying washed objects according to the invention includes cradles for placing and holding washed objects in the drying tank and in the rinsing tank, and the cradle can be moved upward and downward by a hoisting mechanism and can be stopped in a state in which a part of the washed object is in contact with the fluid level directly or indirectly.
The portion of the washed object that is immersed into the fluid level of the rinsing tank of the apparatus for drying washed objects according to the invention is the portion other than the patterned surface.
A method for drying washed objects according to the invention is a method for drying washed objects for performing drying by the use of a drying apparatus including a drying tank having an opening on top thereof so that washed objects can be placed or taken out from above, and a rinsing tank formed integrally with the drying tank, and is capable of being sealed hermetically by closing an openable and closable lid, comprising the steps of moving a cradle for placing and holding washed objects upward and downward by a hoisting mechanism after the washed object was rinsed in the rinsing tank and stopping the same in a state in which a part of the washed object is in contact with the fluid surface directly or indirectly, performing drying process by emitting organic solvent mist to the washed object from a fluid spray nozzle provided on a mist-straightening vane and emitting the same in turn from the mist-straightening vane indirectly, draining deionized water after the drying step, and performing quick drying process by supplying inert gas at a high temperature into the drying tank after the draining step.
In a method for drying washed objects according to the invention, the washed object is wet when the washed object is drawn up from the rinsing tank by the hoisting mechanism.
In a method for drying washed objects according to the invention, the inert gas is nitrogen gas (N2) at normal temperatures or heated nitrogen gas (N2).
In a method for drying washed objects according to the invention, an organic solvent for generating the mist of organic solvent is selected from alcohols, ketones, or ethers having water solubility and capability of lowering surface tension of deionized water with respect to the substrate.
In a method for drying washed objects according to the invention, the diameter of organic solvent mist emitted indirectly from the mist-straightening vane is not more than 20 xcexcm.
In a method for drying washed objects according to the invention, the organic solvent can be heated to temperatures within the range of 5xc2x0 C. to 80xc2x0 C. when it is IPA (Isopropyl alcohol).
In a method for drying washed objects according to the invention, rinsing water for performing rinsing operation in the rinsing tank is hydrogenated water.